This invention relates to an apparatus for providing a controlled supply of an anesthetic gas.
In recent years, various improvements have been made in surgical equipment, in line with advances in medicine generally. However, in the case of the supply of an anesthetic gas, manual control is still the normal method adopted. This presents various disadvantages, including the possibility of operator error and the difficulty of maintaining an accurately controlled supply of the anesthetic gas. At present there is on the market a system for the supply of anesthetic gas which is designed to overcome the effects of operator error by accurately regulating the flow rate of the gas and the mixture ratio in an interlocking manner. However this system, as well as the conventional manual method has the disadvantage that accurate measurement and recording of the progress of the anesthetic process are difficult to accomplish. In addition, these systems utilize a type of gas flow rate meter which becomes inaccurate when the apparatus is tilted.
With the present invention, such disadvantages of the prior art methods are overcome effectively. Flow rates of gases used to constitute the anesthetic gas mixture are monitored by flow rate sensors which produce electrical signals in response. These are applied to an electronic computer, output signals from which regulate the flow of gases by means of actuating electrically controlled throttle valves. In this way, the flow rate and mixture ratio of anesthetic gas are accurately determined in accordance with data stored beforehand in a memory of the electronic computer.